Because we've learned from the Rosetta stone that having more than one language system is extremely helpful for translating things. Translating something like t

Because we've learned from the Rosetta stone that having more than one language system is extremely helpful for translating things. Translating something like this with no knowledge of the human race is an enormous endeavor. By providing three bases (base 1, base 2, and base 10), it'll be much easier to extrapolate their meaning. Base 1 should be fairly universal, and since much of our world today revolves around base 2 and 10, having each of those present will make for an effective starting point. Think of it this way - if an alien probe landed on earth today, wouldn't it be a nice starting point to know that they use a mix of base 7, base 342, and base 61 for their number systems?